I'm on Windows 7 and Minion just started not opening at all no matter what I try. I've completely uninstalled and reinstalled and still nothing. I see it in the Processes tab of Task Manager, and it's eating about 25% of my processing power, but it never appears. Have to "End Task" to close it.

Are you using a 64bit operating system and 64bit Minion? Try the 32bit Minion file as such a behaviour sometimes seems to happen with teh 64bit version.

Oh and please provide the minion.log file so one can check what Minion is doing and where it got stuck.
Some virus scanners and firewalls interfer (Symantec, Bitlocker, etc.) so please define whitelist rules for the minion app and check if this fixes it.

Test the 32bit version of Minion please as the 64bit version is sometimes making trouble on a 64bit OS.
Check your firewall, antivurs and add whitelist entries to them for Minion.
And please: Post your minion.log file and minion.xml files here so one can analyze them!

I am having the same problem for about 2 days. It was running fine for months!Minion.exe (64 bit version) appears in Task Manager Processes but nothing else shows (no program window of any sort).
The exe was using around 120k+ memory btw. I am on Win7 64-bit.

Yea I already tried that command, and now tried it with ipv6, but same issue.
I gave this program full permissions through AV/firewall, and it was working perfectly fine 2 days ago.
I even disabled both to test but no dice.

I contacted my ISP and alerted them about a possible block/proxy.

For now a VPN works fine.

- My question is why though will the window not appear at all?
- Wouldn't it make more sense if the window appears at least, and THEN tells the user that it cannot establish internet connection?

I assume this is a JAVA topic and related to the developing language behaving like this, as an error occurs.
Maybe one can intercept the error and open the window to show a message then at least.
Depends on teh possibilities and the Minion development team.

Did you check if you are using a proxy server in the browser/windows settings like described in multiple other threads already?
Did you test to allow firewall and antivirus for Minion?
Did you test the above metnioned command to fix the problem or read the linked other thread?
Did you test if it works via a VPN?
Show us your minion.log please so we can have a glance where it stops to work.

Well, no idea then as there isn't created any Minion.log file for you at all it seems that the app crashes before it can even create one.
You should run it as adiministrator, don't use special chars (only latin ones) in your windows username (as this breaks Minion too sometimes) and if this all does not help I'm not able to neither sorry.